The US Air Force is facing a fighter pilot shortage as it scrambles to service an ever-growing array of air campaigns around the world, top officials said Wednesday.

The shortfall will likely rise to more than 700 pilots (from a force size of 3,500 fighter pilots) by the end of this fiscal year, and as high as 1,000 in two years time, Air Force Secretary Deborah Lee James and the service's Chief of Staff, General David Goldfein, told reporters.

Goldfein said the situation was a "crisis."

Airlines are increasingly luring military fliers into the private sector, and many are choosing to leave due to the stresses of extended deployments overseas.

The shortage comes as America is engaged in air wars on multiple fronts, including in Iraq, Syria, Afghanistan and Libya. The US military relies heavily on its air dominance to wage war and avoid putting US foot soldiers in harm's way.

The Air Force also faces a shortage of drone pilots, but James said recruitment and retention in that sector had improved.

Officials are announcing a $35,000 bonus for drone operators who sign up under a new contract, and the military is using increasing numbers of contract workers to conduct non-lethal drone patrols.

"It is not all done yet but there is a lot going on," she said.

"We are well on the way to having 100 percent manning at our retraining units and having all those instructors in the schoolhouse means we are going to be producing more (drone) pilots."